1. Field of the Invention
The invention relates to a motor vehicle door lock or the like with a lock latch and a detent pawl which holds the lock latch in the locked position (main catch and optionally a preliminary catch) and with a motorized opening drive, the motorized opening drive having an electric drive motor and having a step-down gear which, on the driven side, engages the detent pawl or a detent pawl lever or the like which moves the detent pawl and lifts the detent pawl when the drive motor is triggered so that the lock latch is released into an open position.
2. Description of Related Art
Motor vehicle door locks or the like with an electrical motor-operated opening drive are known in many embodiments. Recently, especially, pure electric locks have become known; they are motor vehicle door locks which have no mechanical actuating mechanisms or have mechanical operating mechanisms only for emergencies (German Patent DE-C-44 36 617).
One problem in motor vehicle door locks or the like with an opening drive is that opening must be reliably possible even when very high forces which lead to high adhesive friction between the detent pawl and the lock latch in the closed position load the lock latch in the opening direction. This means that the electric drive motor of the opening drive and the step-down gear must be designed such that they still reliably enable opening even in this least favorable case. This leads to the requirement that either the electric drive motor of the opening drive must be made very large, with the consequence that often the opening drive can no longer be accommodated in the housing of the motor vehicle door lock itself (see also German Patent DE-C-44 36 617) and/or that the step-down ratio of the step-down gear must be so large that opening by the opening drive takes an extraordinarily long time. Actuating times of several hundred millisecond are by no means unusual. Accustomed to the opening times of mechanically actuated motor vehicle door locks or the like, these actuation time are perceived as annoyingly long by the user.
Thus, a primary object of the present invention is to devise a motor vehicle door lock or the like with a motorized opening drive which ensures reliable lifting of the detent pawl from the corresponding catch of the lock latch, even with increased force on the locking wedge, with an opening duration which is as short as possible.
The aforementioned object in a motor vehicle door lock or the like is achieved in a lock of the type initially mentioned above by the fact that a lifting spring which acts in the lifting direction of the detent pawl is assigned to the step-down gear or the detent pawl lever or the like, that the lifting spring is tensioned when the opening drive reverses from the open position into the locked position, and that the lifting spring, when the opening drive is advanced from the locked position into the open position, the spring force of the lifting spring reinforces the forward motion and the lifting motion of the detent pawl. In accordance with the invention, to increase the torque necessary for opening the motor vehicle door lock or the like, the torque which is available for lifting the detent pawl, in accordance with the invention, is composed of the torque of the drive motor and the torque of the lifting spring. Also, for increased forces on the locking wedge or on the lock latch, reliable and prompt opening is ensured. Conversely, it is simply necessary for the drive motor of the opening drive to also be loaded during its return motion from the opening position into the closed position, especially by the tensioning of the lifting spring.
In general, it should be pointed out that the teaching of the invention relates to motor vehicle door locks or the like, especially to side door locks, but also to rear door locks, rear hatch locks and hood locks. Furthermore, it should be emphasized that the drive motor of the motorized opening drive will preferably be an electric drive motor, but that, fundamentally, also other drive motors, for example, pneumatic drives or hydraulic motors, can be used.
The teaching of the invention is especially important in conjunction with a keyless motor vehicle door locking system, therefore with automatic identification of the operator, etc. Here, especially prompt opening of the motor vehicle door lock is necessary; this corresponds to natural handling which is customary in mechanical motor vehicle door locks. The approach according to the invention meets these requirement to a special degree.
These and further objects, features and advantages of the present invention will become apparent from the following description when taken in connection with the accompanying drawings which, for purposes of illustration only, show a single embodiment in accordance with the present invention.